Leatherback sea turtle

Taxonomy and Evolutionary History

The leatherback sea turtle is the sole surviving member of its genus Dermochelys and family Dermochelyidae. It was first described scientifically in 1761 by Domenico Agostino Vandelli as Testudo coriacea. The genus name Dermochelys, coined by French zoologist Henri Blainville in 1816, along with the species name coriacea, refer to the turtle's distinctive leathery skin. While older common names include 'lute turtle' or 'trunk turtle', the modern name directly describes its unique carapace. Relatives of the modern leatherback have existed in a similar form since the first true sea turtles evolved over 110 million years ago during the Cretaceous period. Genetic studies indicate the leatherback's family split from the family containing all other living sea turtles approximately 49 to 70 million years ago. The only known fossil of the extant species itself is a humerus bone from Pleistocene sediments in the Taiwan Strait.

Anatomy and Unique Physiology

The leatherback possesses a highly hydrodynamic, teardrop-shaped body powered by enormous front flippers that can span up to 2.7 metres tip to tip. Its most defining anatomical feature is the absence of a bony carapace. Instead, its back is covered by thick, oily skin embedded with tiny bone plates called osteoderms. Seven prominent ridges run the length of its dark grey to black back, with a lighter coloured underside. The turtle lacks teeth but has pointed cusps on its upper jaw and backward-pointing spines in its throat to help capture and swallow soft-bodied prey. Adults average 1 to 1.75 metres in curved carapace length and 250 to 700 kilograms in weight, with the largest verified specimen weighing 650 kilograms. Leatherbacks exhibit several adaptations for life in cold water, including extensive fat insulation and networks of blood vessels that act as countercurrent heat exchangers in their flippers and trachea.

This unique physiology enables remarkable feats. Leatherbacks are one of the deepest diving marine animals, recorded at depths of 1,280 metres, and are the fastest-moving reptiles, with one speed recorded at 35.28 km/h. They maintain a high core body temperature through constant activity and their specialised anatomy, with adults found with body temperatures up to 18 degrees Celsius above the surrounding water. Their flexible, leathery carapace, connected by interlocking sutures between osteoderms, allows it to withstand immense pressure during deep dives and expand and contract with the lungs.

Global Distribution and Subpopulations

The leatherback sea turtle has the widest global distribution of any reptile, found in all tropical and subtropical oceans and ranging into the Arctic Circle. Globally, there are three major genetically distinct populations in the Atlantic, eastern Pacific, and western Pacific Oceans, with a possible fourth in the Indian Ocean. Recent estimates suggest only 26,000 to 43,000 females nest globally each year, a dramatic decline from an estimated 115,000 in 1980. The Atlantic population ranges from the North Sea to South Africa, with significant nesting in Suriname, French Guiana, Gabon, and Trinidad and Tobago. This population forages in colder waters, including the Gulf of Saint Lawrence and off Newfoundland and Labrador.

The Pacific population is divided into eastern and western groups and is at the greatest risk of extinction. The western group nests in Indonesia and the Solomon Islands and forages along the North American west coast. The eastern group nests mainly in Mexico and Costa Rica and forages off South America. The World Wildlife Fund estimates only about 2,300 adult female Pacific leatherbacks remain. A nesting population in Malaysia, which once hosted 10,000 nests annually at Rantau Abang, has been effectively eradicated primarily due to egg harvesting, with only infertile nests recorded in recent years. Little is known about the Indian Ocean subpopulation, which nests in Sri Lanka and the Nicobar Islands.

Ecology, Diet, and Migration

Leatherback sea turtles are pelagic, spending most of their lives in the open ocean on epic foraging migrations. They are obligate feeders on gelatinous zooplankton, with adult diets consisting almost entirely of jellyfish. This diet influences jellyfish populations. They also consume other soft-bodied organisms like salps, siphonophores, and squid. An adult leatherback can consume roughly 73 percent of its body weight in jellyfish daily. Their hunting strategy leads them into extremely cold waters, with one individual recorded actively foraging at 0.4 degrees Celsius. Pacific leatherbacks migrate approximately 9,700 kilometres from nesting beaches in Indonesia to feed on jellyfish blooms off California.

One tracked individual swam 20,000 kilometres from Indonesia to the United States over 647 days. These migrations make them seasonal visitors to Canadian waters. They follow their diurnally migrating prey, preferring deeper waters during the day and shallower waters at night. Their deep dives, beyond 1,000 metres, exceed the physiological limits of all other diving reptiles and most marine mammals. Their favoured nesting beaches are mainland sites facing deep water, and they typically avoid areas protected by coral reefs.

Conservation Status and Threats

The leatherback sea turtle is listed as endangered under the U.S. Endangered Species Act and is protected as an endangered species under Canada's Species at Risk Act. The global population is estimated to have declined by 40 percent over the past three generations. The most precipitous declines are in the Pacific, where eastern Pacific nesting has dropped by over 90 percent and the western Pacific's largest remaining population in Indonesia has declined by over 80 percent. The primary threats are universal across their range. Incidental capture in fishing gear, or bycatch, is a leading cause of mortality. On nesting beaches, eggs are harvested for human consumption, and turtles are hunted, while coastal development causes habitat loss and erosion.

In the marine environment, plastic pollution is a severe and growing threat. Leatherbacks frequently mistake floating plastic bags for jellyfish. A global study found more than 30 percent of dead leatherbacks examined had plastic in their intestines. Ingestion can cause fatal internal injuries, intestinal blockage leading to starvation, and increased buoyancy that hampers diving and reproduction. In California, a major foraging area, an estimated one-third of adult leatherbacks have ingested plastic. Other threats include boat strikes, contamination, and the broad impacts of climate change on prey availability, nest temperature, which determines sex ratios, and beach erosion.

Leatherbacks in Canadian Waters

Leatherback turtles are significant, though rare, visitors to both of Canada's coastlines, protected under the federal Species at Risk Act. In the Atlantic, they forage in the Gulf of Saint Lawrence near Quebec and as far north as Newfoundland and Labrador, taking advantage of seasonal jellyfish blooms. In the Pacific, they are observed off the coast of British Columbia, with waters off Haida Gwaii and near the mouth of the Columbia River being important areas. Since 1931, there have been 152 leatherbacks documented off the coast of British Columbia, with 91 percent of those sightings involving live animals. A leatherback was sighted off Langara Island in July 2025.

The cold, productive waters off British Columbia are extremely important foraging habitat for the critically endangered Pacific population that migrates from nesting sites in Indonesia. Public awareness and reporting of sightings are valuable for conservation research. Canadians are encouraged to report sightings on the Atlantic coast through the Canadian Sea Turtle Network and on the Pacific coast to the toll-free number 1-866-I-SAW-ONE. Threats in Canadian waters mirror global ones, with entanglement in fishing gear and debris, boat collisions, and plastic pollution being of particular concern for these migrating giants.

Lifespan and Reproduction

Very little is definitively known about the leatherback's lifespan, with estimates ranging from 30 to over 100 years. In 2020, researchers from Australia's CSIRO used genetic markers to estimate the natural lifespan of marine turtles. Leatherbacks bear the heaviest clutches of eggs of any sea turtle. Their reproduction is threatened by temperature dependent sex determination, where the temperature of the nest determines the sex of the hatchlings.

Nesting is a precarious time for females, who must come ashore on sandy beaches. The loss of nesting habitat to coastal development and erosion is a major threat. In the Northwest Atlantic, nesting numbers had been increasing but have shown significant decreases in recent years at key locations like Florida. In the Pacific, the catastrophic decline in nesting females is the clearest indicator of the species' dire status. The survival of hatchlings is also perilous, as they average only 61.3 millimetres in length and 46 grams in weight when they emerge and must make their way to the ocean facing numerous predators.

Research and Recovery Efforts

Organisations like NOAA Fisheries are dedicated to conserving and recovering leatherback populations worldwide through innovative techniques and partnerships. For the most at risk Pacific populations, NOAA has identified them as a 'Species in the Spotlight', prioritising recovery efforts to prevent extinction. Recovery actions include developing and implementing regulations, funding research and monitoring projects, and working with partners to reduce bycatch. A key tool in bycatch reduction is the Turtle Excluder Device, a grid installed in shrimp trawl nets that allows turtles to escape. Research using satellite tracking has been instrumental in mapping the incredible migrations of leatherbacks and identifying critical foraging habitats like those off Canada.

Public education campaigns highlight the threat of plastic pollution, illustrated by videos showing how easily a leatherback mistakes a plastic bag for a jellyfish. In California, a major foraging zone, a ban on single use plastic bags was implemented in 2016 to help address this threat. Conservation efforts also focus on protecting key nesting beaches in Central Africa, South America, and Indonesia. In Canada, raising awareness through initiatives like #leatherbacksinbc helps gather valuable sighting data and engages the public in the stewardship of these endangered visitors to Canadian waters.

Questions about Leatherback sea turtle

Are there leatherback sea turtles in Canada?

Yes, leatherback sea turtles are seasonal visitors to both Canadian coasts. In the Atlantic, they forage in the Gulf of Saint Lawrence and off Newfoundland. In the Pacific, they are found off the coast of British Columbia, with 152 documented sightings since 1931. They are protected as an endangered species under Canada's Species at Risk Act. The cold, jellyfish-rich waters are important feeding grounds for turtles that migrate from as far away as Indonesia.

Why is the leatherback turtle endangered?

Leatherback turtles face multiple severe threats leading to their endangered status. The primary causes are incidental capture in fishing gear, hunting of turtles and harvesting of their eggs, and habitat loss on nesting beaches. Marine plastic pollution is a critical threat, as turtles mistake bags for jellyfish. In the Pacific, populations have declined by over 90 percent, making them most at risk. Climate change also impacts nest temperatures and prey availability.

How big can a leatherback turtle get?

The leatherback is the largest of all living turtles. Adults typically range from 250 to 700 kilograms in weight and 1 to 1.75 metres in curved carapace length. They can reach total lengths of up to 2.7 metres. Their front flippers alone can span 2.7 metres from tip to tip, which are the largest in proportion to body size of any sea turtle.

What do leatherback sea turtles eat?

Adult leatherback turtles are specialised feeders that subsist almost entirely on jellyfish. This diet influences jellyfish populations in the oceans. They also consume other soft-bodied organisms like salps, siphonophores, and squid. An adult can eat roughly 73 percent of its body weight in jellyfish each day. Their obligate feeding on jellyfish is what leads them on long migrations to productive areas like the waters off British Columbia and California.

How deep can a leatherback turtle dive?

Leatherback turtles are among the deepest diving marine animals. They have been recorded diving to depths of 1,280 metres, which is deeper than most marine mammals. Typical dives last between 3 and 8 minutes, but they can remain submerged for 30 to 70 minutes on occasion. Their unique physiology, including a flexible leathery carapace and specialised heat retention systems, allows them to hunt in these deep, cold environments where their jellyfish prey are found.

What should I do if I see a leatherback turtle in Canada?

If you spot a leatherback turtle in Canadian waters, it is valuable to report the sighting to aid research and conservation. For sightings off the Pacific coast of British Columbia, you can call 1-866-I-SAW-ONE. For sightings on the Atlantic coast, reports can be made through the Canadian Sea Turtle Network. Providing details like location, date, time, and the turtle's condition helps scientists track their movements and identify critical habitats. Always observe from a safe distance to avoid disturbing the animal.

Sources: Wikipedia and current public reporting, checked by the Your Space Hamilton desk. Last updated 2026-10-23.